From: Keith Fahlgren <keith@...>
Date: 2005-07-29T22:34:02+09:00
Subject: Re: Sed -> Ruby : .. and ...

Hi all,

Thanks for the helpful responses. Many corrected me, rightly, for 
writing a whole program rather than just using a one-liner and for 
modifying the file in place rather than setting up temporary files. I 
was concentrating on my task, making a template to replace thousands of 
lines of sed files rather than doing a single replacement.

My larger problem still revolved around doing a bunch matches inside an 
range. 

On Thursday 28 July 2005 5:46 pm, mathew wrote:
> working_file.gsub!(/(?=BEGIN RANGE)(.*?)(?=END RANGE)/m) {||
>    $1.gsub(/MATCH/m, 'REPLACEMENT')
> }

Matthew pointed out an easier way to get around it but I had rejected 
that method from the start because I wanted to be able to nest ranges 
(like I can in sed).

I think the problems with my inital attempts was assuming .read was 
returning an array rather than a string. Slapping .to_a to the end 
solved that bit and the program now works as expected, I think.

Here's my solution (though I'd still love comments):


#!/usr/bin/env ruby
files = ARGV

files.each do |arg|
  puts "\nOpening file #{arg}"
  f = File.open(arg)
  working_file = f.read.to_a
  f.close
  working_file.each do |aline|
    if aline =~ /BEGIN RANGE/ .. aline =~ /END RANGE/   
      #nest if lines like above as many times as needed for nested 
ranges	
      aline.sub!(/MATCH/,'REPLACEMENT')
    end
  end

  puts "\nDoing ACTION in #{arg}"
  fnew = File.new("#{arg}.tmp", "w")
  puts "\nWriting #{fnew} now"
  fnew.print(working_file)
  fnew.close
end



Thanks,
Keith